The invention relates to an arrangement for open-end friction spinning with two adjacently arranged friction rollers driven in the same rotational direction and forming a wedge shaped yarn forming gap. An inlet and opening device is provided for opening and feeding single fibers to the wedge shaped gap and a yarn withdrawal device is provided for drawing off the yarn being produced in the longitudinal direction of the wedge shaped gap.
With a known construction of the kind mentioned above (DE-PS) No. 27 20 625, the fibers separated by an opening roller arranged parallel to the axis, are spun off and reach the wedge gap essentially in a free flight. The direction of fiber flight is restricted by guide walls extending in the longitudinal direction of the wedge gap. Since the quality of the yarn to be spun is decisively dependent upon the orientation of the fibers and the deposition of same parallel to each other and preferably extended in the longitudinal direction of the wedge gap, the known construction provides for a centrifugal disk protruding with teeth into the fiber flight space, whereby the teeth move essentially in the direction of the yarn withdrawal. Thereby, the fibers are to receive a motion impulse in the yarn withdrawal direction so that they are largely parallel for spinning purposes. It is, however, questionable whether the desired orientation of the fibers is herewith sufficiently obtained, because this arrangement apparently did not consider that the fibers are supplied with a speed essentially higher than the yarn withdrawal speed of the yarn being produced, so that almost inevitably these fibers are shoved or compressed and take up a tangled position when reaching the area of the wedge gap. The danger of shoving of the fibers is even further increased in that the centrifugal disk means additionally accelerates the fibers. It is furthermore unfavorable that such centrifugal disk requires a drive means which leads to an increase in energy consumption.
It is an object of this invention to design an arrangement of the kind mentioned above to thereby eliminate or decrease the danger of shoving and tangling of fibers when they reach the area of the wedge gap.
This object is acheived according to the invention by providing a closed fiber feed channel between the inlet and opening device and the friction rollers, which fiber feed channel contains means for reducing the flight speed of the fibers.
It was realized with the invention that the speed cannot essentially be reduced with respect to the fibers being spun off the opening roller, because the quality of opening would be impaired if the opening roller were slowed down. The invention thereby involves the concept of reducing the flight speed or transportation speed of the fibers to a range corresponding as closely as feasible to the speed of yarn withdrawal so that the fibers are no longer shoved (tangled) when reaching the area of the wedge gap. Thereby, a much better fiber deposit and simultaneously a better yarn quality is obtained in connection with the guiding of fibers within the closed fiber feed channel. In preferred embodiments of the invention the fiber feed channel is provided with control or guide elements protruding into the flight path of the fibers. These stationarily arranged control elements form an obstacle upon which the fibers hit so that they are mechanically slowed down. They are subsequently accelerated and drawn by means of the transportation air stream controlled within the fiber feed channel.
In order to prevent the fibers from getting caught on the control elements, it is advantageous according to certain embodiments to provide the control elements with a smooth, low friction surface. To serve the same purpose, it is provided in certain further embodiments that the control elements are attached to a channel wall and end at a spacing from the opposite channel wall. It is further provided in preferred embodiments that the control elements are bent in the flight direction of the fibers. It is thereby obtained that also fibers, in the event they wind around the control element, are carried away by the transportation air stream and do not get stuck. In order to additionally straighten the fibers, further embodiments provide that the control elements divide the fiber feed channel in the longitudinal direction into several lanes. In this manner, the transportation air stream occurring within the fiber feed channel can be corrected and controlled.
In still another embodiment of the invention, it is provided that a channel wall is designed as a detachable cover to which the control elements are attached to. This simple means makes it possible to check on the control elements. Additionally, it is also possible to choose the guide elements or control elements that are most suitable in form and arrangement dependent upon the fiber material to be processed, whereby only the cover with the corresponding control elements has to be exchanged.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.